This invention pertains to wireless networking systems and, more particularly, to a wireless network access point which provides the resources of a backbone network to wireless clients. The access point is able to balance loads by deferring association of new clients and thereby directing clients to associate with alternative access points having improved backbone connectivity.
Within the past two decades, the development of raw computing power coupled with the proliferation of computer devices has grown at exponential rates. This phenomenal growth, along with the advent of the Internet, has led to a new age of accessibility to other people, other systems, and to information.
The simultaneous explosion of information and integration of technology into everyday life has brought on new demands for how people manage and maintain computer systems. The demand for information technology professionals is already outpacing supply when it comes to finding support for someone to manage complex, and even simple computer systems. As access to information becomes omnipresent through personal computers, hand-held devices, and wireless devices, the stability of current infrastructure, systems, and data is at an increasingly greater risk to suffer outages. This increasing complexity, in conjunction with a shortage of skilled information technology professionals, points towards an inevitable need to automate many of the functions associated with computing today.
Autonomic computing is one proposal to solve this technological challenge. Autonomic computing is a concept to build a system that regulates itself much in the same way that a person's autonomic nervous system regulates and protects the person's body.
Within the past decade, there has been accelerated growth in portable computing to meet the demands of a mobile workforce. This voluminous mobile workforce has traditionally relied on a cable connection to a backbone network in order to have access to resources such as printers, e-mail servers,
databases, storage, and even Internet connections. Within the past few years alone, the industry has seen rapid deployment of wireless local area networks which offer increased convenience over cable connections to backbone networks. In addition to convenience, wireless networks offer the ability to roam while maintaining a network connection.
Recently, a standard for wireless local area networks known as the IEEE 802.11 standard has been adopted and has gained acceptance among the industrial, scientific and medical communities. The IEEE 802.11 standard for wireless networks is a standard for systems that operate in the 2,400-2,483.5 MHz industrial, scientific and medical (ISM) band. The ISM band is available worldwide and allows unlicensed operation of spread spectrum systems. The IEEE 802.11 RF transmissions use multiple signaling schemes (modulations) at different data rates to deliver a single data packet between wireless systems.
In a wireless local area network, wireless clients obtain access to resources on the backbone network through the use of an access point. The backbone network is typically on a wired network, such as ethernet, but can also be a second wireless network or any combination thereof. When an access point provides connectivity to resources directly on a wired network, the access point will contain, amongst other things, a wired LAN interface, a bridge function, and a wireless LAN interface in order to bridge traffic between the wireless network and the wired network.
Most installations use wireless local area networks as an overlay to an existing ethernet (cabled or wired) network which serves as a backbone or provides access to a backbone and its resources. Typically, access points are provided at various locations to create continuous geographical coverage for the wireless network. Since 802.11 is limited to 30 meters in range and Ethernet is physically limited to 100 meters in length, office environments typically deploy several access points on different backbones. The various wireless access points are assigned to different wireless frequency spectra or channels to allow overlap between wireless ranges.
Wireless clients are implemented such that they associate with an access point based on which access point is detected first or by a predetermined user preference list. Clients beacon for access and, according to present practice, all access points within reach of the beacon respond. Clients connect to the access point that its highest on the predetermined user preference list. Where there is no match between access points on the predetermined user preference list and the access points responding, the client will connect to the access point having the highest signal quality. Based on the connection, the client associates and remains associated with that access point as long as the connection remains, regardless of the number of clients.
A problem arises, however, as a result of clients associating based on highest signal quality or preference list order. It has been discovered that such a technique for associating tends to crowd clients around certain access points while leaving other access points relatively unused even though their signal quality is acceptable. Passive scanning devices aggravate the problem by listening for traffic which more often than not leads the client to associate with access points which are already crowded. If a small percentage of clients start moderate throughput transfers, the majority of clients will have little bandwidth available. In this scenario, all clients being serviced by the access point will experience degradation in performance. Meanwhile, other reachable access points may have less traffic and therefore better bandwidth. This unbalanced access point load is problematic because users are left waiting when attempting to access network resources. Additionally, capital invested on infrastructure is wasted since additional access points have been provided but tend to remain unutilized.
A challenge found, however, is in mitigating imbalanced access point load according to autonomic computing principles.